nfrstrctr s th st f fclts nd systms tht srv cntry, cty, r thr r, nd ncmpsss th srvcs nd fclts ncssry fr ts cnmy, hshlds nd frms t fnctn. nfrstrctr s cmpsd f pblc nd prvt physcl strctrs sch s rds, rlwys, brdgs, rprts, pblc trnst systms, tnnls, wtr spply, swrs, lctrcl grds, nd tlcmmnctns (ncldng ntrnt cnnctvty nd brdbnd ccss). n gnrl, nfrstrctr hs bn dfnd s "th physcl cmpnnts f ntrrltd systms prvdng cmmdts nd srvcs ssntl t nbl, sstn, r nhnc sctl lvng cndtns" nd mntn th srrndng nvrnmnt.
spclly n lght f th mssv sctl trnsfrmtns ndd t mtgt nd dpt t clmt chng, cntmprry nfrstrctr cnvrstns frqntly fcs n sstnbl dvlpmnt nd grn nfrstrctr. cknwldgng ths mprtnc, th ntrntnl cmmnty hs crtd plcy fcsd n sstnbl nfrstrctr thrgh th Sstnbl Dvlpmnt Gls, spclly Sstnbl Dvlpmnt Gl 9 "ndstry, nnvtn nd nfrstrctr".
n wy t dscrb dffrnt typs f nfrstrctr s t clssfy thm s tw dstnct knds: hrd nfrstrctr nd sft nfrstrctr. Hrd nfrstrctr s th physcl ntwrks ncssry fr th fnctnng f mdrn ndstrl scty r ndstry. Ths nclds rds, brdgs, nd rlwys. Sft nfrstrctr s ll th nstttns tht mntn th cnmc, hlth, scl, nvrnmntl, nd cltrl stndrds f cntry. Ths nclds dctnl prgrms, ffcl sttstcs, prks nd rcrtnl fclts, lw nfrcmnt gncs, nd mrgncy srvcs.